As businesses increasingly rely on computers for their daily operations, managing the vast amount of business information generated and processed has become a significant challenge. Most large businesses have a wide variety of application programs managing large volumes of data stored on many different types of storage devices across various types of networks and operating system platforms. These storage devices can include tapes, magnetic disks, optical disks, and other types of storage devices.
Today, storage area networks (SANs) can be used to provide hundreds of storage devices for use by several hosts. Allocating storage devices for use by a particular application program can be a difficult task when the storage devices are provided via a SAN. One approach to making storage devices easier to use and configure is to create an abstraction that enables storage to be viewed in terms of logical storage devices, rather than in terms of the physical devices themselves. For example, physical devices can be logically combined into a single logical storage device that provides the storage capacity of the combined physical storage devices. Such logical storage devices are referred to herein as “logical volumes.” Logical volumes are abstractions consisting of an array of logical memory blocks that store data. While it is said that logical memory blocks store data, in reality the data is stored in physical memory blocks of the underlying physical devices (e.g., hard disks) allocated directly or indirectly to the logical volume.
Configuring a logical volume is a complex task when tradeoffs between performance, reliability, and cost are taken into account. AQ storage administrator must keep track of how particular volumes are implemented so that subsequent reconfigurations of a logical volume do not render the logical volume unsuitable for the purpose for which the logical volume was created. Finally, when a large amount of data is stored using a large number of logical volumes, it is possible that some physical storage devices are allocated to logical volumes such that resources are wasted. Utilization of storage with a certain unintended characteristic can prevent the creation of other logical volumes due to unavailability of those resources.
A solution is needed that allocates resources (e.g., physical storage devices) for multiple logical volumes so that resources are best used to meet organizational needs. The resources allocated should be suitable for the purpose for which the logical volume was created.